In the technical field of transducers miniaturization is one of the major research interests. At the same time, typical performance figures of the transducers, such as signal-to-noise ratio or dynamic range should be maintained at a reasonable level. Micro electrical mechanical systems (MEMS) have been targeted for these applications as they are potentially small scaled, on the order of tens of micrometers, and for their compatibility with semiconductor-like processes. This leads to potentially large volume manufacture. Devices that can be achieved using MEMS fabrication processes are, for example, pressure sensors, ultrasonic transducers, loudspeakers, and microphones. Typically these devises comprise one or more membranes with electrodes for read-out/drive deposited on the membranes and/or a substrate. In the case of electrostatic MEMS pressure sensors and microphones, the read-out is usually accomplished by measuring the capacitance between the electrodes. In the case of transducers functioning as actuators, such as loudspeakers, the device is driven by applying a potential difference across the electrodes.
Typically, the membrane of a MEMS transducer is manufactured using a sacrificial layer, for example, silicon oxide SiO2. In use, the amplitude of the membrane movement is typically limited by approximately the thickness of the sacrificial layer because of structures formed on the sacrificial layers during the manufacturing process prior to (partly) removing the sacrificial layer, thus leaving the formed structures.